Keyboard instrument equipped with speakers

1. A keyboard instrument comprising: a musical instrument case; a speaker which emits sounds in response to instructions from a keyboard section; and a keyboard lid which is switchable between a first arrangement state in which the keyboard lid covers at least a portion of the keyboard section and a second arrangement state in which the keyboard lid is opened to expose at least a portion of the keyboard section and housed in the musical instrument case, wherein the musical instrument case is provided with a sound emission hole penetrating a top plate of the musical instrument case in a vertical direction and an opening section located in front of the top plate, and wherein the keyboard lid, in the second arrangement state, is arranged so as to partition a space in the musical instrument case into a first acoustic space for leading the sounds emitted from the speaker to the sound emission hole and a second acoustic space for leading the sounds emitted from the speaker to the opening section.

2. The keyboard instrument according to claim 1 , wherein the first acoustic space is located on a rear side of the musical instrument case.

3. The keyboard instrument according to claim 1 , wherein the speaker is provided on a rear portion of an undersurface of the musical instrument case, wherein the sound emission hole is provided in a rear portion of the top plate of the musical instrument case, and wherein at least a part of the keyboard lid, in the second arrangement state, is arranged so as to be upright in a rear part of the musical instrument case, from a bottom surface direction of the musical instrument case toward an upper surface direction of the musical instrument case.

4. The keyboard instrument according to claim 3 , wherein the keyboard lid includes a front lid and a rear lid, and wherein, in the second arrangement state, the rear lid of the keyboard lid is substantially vertically arranged and the front lid of the keyboard lid is substantially horizontally arranged.

5. The keyboard instrument according to claim 3 , wherein the part of the keyboard lid, in the second arrangement state, is arranged so as to tilt rearward in the rear part of the musical instrument case, and wherein the first acoustic space gradually narrows from a lower side thereof toward an upper side thereof.

6. The keyboard instrument according to claim 3 , wherein a length of the sound emission hole in a front-to-rear direction is narrower than a length of an upper side of the first acoustic space in the front-to-rear direction.

7. The keyboard instrument according to claim 1 , wherein the opening section has an opening diameter corresponding to a horizontal width of the keyboard section, and wherein the sound emission hole is provided in a portion of the top plate corresponding to the speaker.

8. The keyboard instrument according to claim 7 , wherein the sound emission hole has an opening diameter corresponding to an outer diameter of the speaker.

9. A keyboard instrument, comprising: a musical instrument case; a speaker which emits sounds in response to instructions from a keyboard section; and a keyboard lid which is switchable between a first arrangement state in which the keyboard lid covers at least a portion of the keyboard section and a second arrangement state in which the keyboard lid is opened to expose at least a portion of the keyboard section and housed in the musical instrument case, wherein the musical instrument case is provided with an opening section, wherein the keyboard lid, in the second arrangement state, is arranged such that a first acoustic space for leading the sounds emitted from the speaker to the opening section is formed between the keyboard lid and a rear plate of the musical instrument case, and wherein the opening section has provided thereon a diffuser which provides directivity to the sounds emitted from the speaker to outside of the musical instrument case.

10. A keyboard instrument, comprising: a musical instrument case; at least one speaker which emits sounds in response to instructions from a keyboard section; and a keyboard lid which is switchable between a first arrangement state in which the keyboard lid covers at least a portion of the keyboard section and a second arrangement state in which the keyboard lid is opened to expose at least a portion of the keyboard section and housed in the musical instrument case, wherein the at least one speaker includes a first speaker and a second speaker, wherein the musical instrument case is provided with a first sound emission hole provided in a portion of an upper surface of the musical instrument case corresponding to the first speaker, and a second sound emission hole provided in a portion of the upper surface of the musical instrument case corresponding to the second speaker, and wherein the keyboard lid, in the second arrangement state, is arranged such that a first acoustic space for leading the sounds emitted from the first and second speakers to the first and second sound emission holes is formed between the keyboard lid and a rear plate of the musical instrument case.

11. A keyboard instrument comprising: a musical instrument case; a speaker which emits sounds in response to instructions from a keyboard section; and a keyboard lid which is switchable between a first arrangement state in which the keyboard lid covers at least a portion of the keyboard section and a second arrangement state in which the keyboard lid is opened to expose at least a portion of the keyboard section and housed in the musical instrument case, wherein the musical instrument case is provided with an opening section, wherein the keyboard lid, in the second arrangement state, is arranged such that a first acoustic space for leading the sounds emitted from the speaker to the opening section is formed between the keyboard lid and a rear plate of the musical instrument case, wherein the speaker is provided facing upward on an undersurface of a bottom portion of the musical instrument case, wherein the bottom portion of the of musical instrument case has a sound reception hole provided corresponding to the speaker so as to take the sounds emitted from the speaker into the musical instrument case, wherein the sound reception hole includes a front side hole provided in an area under the keyboard section, and a rear side hole provided rearward of the front side hole in an area behind the keyboard section, and wherein the rear side hole is provided at a position and has a width such that, in a state where the keyboard lid hangs down in a rear part of the musical instrument case while being opened to expose the keyboard section, the rear side hole is opened from a position in front of a rear end of the keyboard section to a position behind the rear end of the keyboard section that corresponds to the first acoustic space, and such that the sounds emitted from the speaker and passing through the rear side hole are separated toward a front side and a rear side of the keyboard lid.

12. The keyboard instrument according to claim 2 , wherein the speaker is provided facing upward or provided at a tilt so as to be oriented toward an anterosuperior direction in the musical instrument case.

13. The keyboard instrument according to claim 10 , wherein the first speaker is provided facing upward on an undersurface of a bottom portion of the musical instrument case, wherein the bottom portion of the of musical instrument case has a sound reception hole provided corresponding to the first speaker so as to take the sounds emitted from the first speaker into the musical instrument case, and wherein the second speaker is provided facing upward or provided at a tilt so as to be oriented toward an anterosuperior direction in the musical instrument case.

14. The keyboard instrument according to claim 1 , wherein the speaker has a diffuser provided on an upper front side thereof which provides directivity toward a direction of the second opening section to the sounds emitted from the speaker.

15. The keyboard instrument according to claim 10 , wherein the first speaker is a full-range speaker and the second speaker is a speaker for high-pitched sounds.

16. The keyboard instrument according to claim 11 , further comprising a second opening section, the first and second opening sections being provided at respective positions such that, after the sounds emitted from the speaker and passing through the rear side hole have been separated toward the front side and the rear side of the keyboard lid, the respective separated sounds are emitted from the second and first opening sections, respectively.